Rotational Bands inTm168from theTm169(d,t)Tm168Reaction

The ${}_{}{}^{169}{}_{}{}^{}\mathrm{Tm}(d,t){}_{}{}^{168}{}_{}{}^{}\mathrm{Tm}$ reaction has been studied at an incident deuteron energy of 17.0 MeV. The excitation energies of more than 55 states up to 1.5 MeV in the residual nucleus were obtained to an accuracy of ±0.15%, and the ground-state $Q$ value for the ${}_{}{}^{169}{}_{}{}^{}\mathrm{Tm}(d,t){}_{}{}^{168}{}_{}{}^{}\mathrm{Tm}$ reaction was measured to be $Q_0=-1775\mathrm{}\pm 6$ keV. Differential cross sections were measured at 2.5° intervals from $7.5°\le {\theta }_{\mathrm{lab}}\le 45°$, and then at 5° intervals for $45°\le {\theta }_{\mathrm{lab}}\le 90°$ for most of these transitions. The resulting angular distributions were found to be well described by distorted-wave calculations for almost all transitions observed. The $l$-transfer values deduced for these transitions allowed the assignment of a narrow range of $J^{\pi }$ values to the corresponding states in ${}_{}{}^{168}{}_{}{}^{}\mathrm{Tm}$, independent of arguments based on the Nilsson-model predictions of transition strengths. Several anomalous angular distributions to presumably well-known rotational states which apparently cannot be explained by the distorted-wave calculations are discussed. Spectroscopic factors for all the observed transitions were computed and are compared to the Nilsson-model predictions for low-lying negative-parity bands. Transition-strength anomalies are discussed.